Electric fuse



Patentecl July 14,` 1925.

UNITED STATES 'WILFOBD J. HAWKIN'S, OF IEONTCLAIR NEW JERSEY.

ELECTRIC FUSE.

Application filed February 25, 1920. Serial No. &361,318.

To all whom it may concem: p

Be it known that I, WILFORD J. HAwKINs, a citizen of the United States,residing at Montclair, in the county of Essex, State of New Jersey, haveinvented certain new and useful Improvements in Electric Fuses; and I dohereby declare the following to be a full, clear, and exact descriptionof the inventon, such as will enable others skilled in the art to whichit appertains to make and use the same.

This invention relates to electric fuses and is directed to theprovision of a fuse of an improved construction which is very effectivein suppressing the are formed when the fusible link is burned out, inwhich the channel for the reception of the fusible link is of thesmallest cross-section permissible, in which the fuse body is of greatstrength and which may be manufactured at low cost.

In the attainment of the foregoing objects I employ a fuse body made ofa moldable insulating material possessing great strength, such, :Eorinstance, as bakelite, condensite or other similar material. This fusebody is preferably molded to the form of a cylinder having an axialpassage therethrough which is of substantially the same cross-sectionalshape as the fusible link. In this way a fuse body is produced which isof such great strength as to practicall eliminate the danger ofbreakageof the ody by the explosion which occurs when the fusible linkis burned out. Furtherrnore, the small size of the opening through thefuse body for the link removes the danger that an operator will employtwo links together and thereby increase the carrying capacity of thefuse to such extent as to make it useless as a protective device. i

If desirecl, in order to simplifythe work of molding the fuse body, thelatter may be formed in two parts each substantially semieircular incross-section and each having half of the groove for the fuse linkformed therein. When this is done I prefer to provide coacting ribs andgrooves upon the abutting surfaces of the two parts of the fuse body sothat a tortuous path is provided froni the interior to the exterior ofthe fuse body thereby restricting the freedom of flow from the interiorto the eXterior of the fuse of gases developed when the link is burnedout.

The pre ferred embodiment of the invention is illustratedin the drawingsannexed hereto in which Fig. 1 is a central longitudinal section of thefuse; Fig. 2 is a transverse section on line 2-2 of Fig. 1; Fig. 3 is aview of a form of fuse' link which may be employed and Figs. tto 10inclusive are transverse sectional views corresponding to Fig. 2 andillustrating modified forms of the fuse body which may be employed.

Referring to these drawings, 11 indicates a fuse body made of moldableinsulating material such as bakelite or condensite. It is of cylindricalform With threads upon its ends and with a central passage through itfor the reception of the fusible link 12. This central passage is of thesame cross-sectional shape as the link 12 and is of substantially thesame size as the link. It approximates the size of the link so closelythat it is impossible to insert two links in the passage and therebyincrease the carrying Capacity of the fuse without rupture of the link.

On the ends of the fuse body are end caps to which the ends of the linkare electrically connected. These end caps 13 and 14 are interiorlythreaded to coact with the threads upon the ends of the body 11. One end15 of the link 12 is bent at a right angle to extend along the end ofthe body 11 and when the end cap 14 is tightened up on the threaded endof the body 11, the end 15 of the link is gripped between the body 11and the end of the end cap 14, thus making good electrical connectionbetween the end cap 1 1 and the end 15 of the link.

At the other end of the fuse 'the link is similarly gripped by the endcap 13 but at this 'end a Washer 16 is provided. This Washer is in theform of a disc with a notch cut in its periphery and the end of the link12 is bent along the face of the body 11, then through the notch in thewasher 16 and then along the face of the Washer. This Construction issuch that by tightening np the end cap 18 the end of the link 12 isgripped between the Washer 16 and the end of the end cap 13 and aportion of the end of the link 12 is eXposed through an opening 17 inthe end cap 13 so that the rating of the fuse stamped upon the end ofthe link 'may be read throu h the opening 17.

If desira le, the fuse link 12-may have a thin coating of asbestos 18applied thereto by means oi waterglass or other suitable cementso as toprevent scorching or carbonizing the walls of the passage for the linkthrough 'the non-Contacting fse body 11 lOU In Fgs. 1 and 2 the .fusebody 11 is shown asintegral. If desired, however, especially for thepurpose of reducing the manufacturing cost, the fuse body may be formedin two parts each of more or less semi-circular cross-section. In' Fig.4 the fuse body is shown as formed of two parts, the division betweenthe two parts being transverse to the plane of the opening for the fuselink.

In Fig. 5 the construction is the same except that the division is inthe plane of the opening for thelink. In Figs. 6 to '10 inclusiveconstructions are shown corresponding to Figs. 4 and 5 except that ribs19 and grooves are provided upon the abutting faces of the two, partsof' the fuse body. 'The ribs and grooves ma'y be rounded as shown inFigs. 7 and 8 or square as shown in Fig. 9 or dovetailed as shown inFig. 10. All of these constructions provided for a tortuous path fromthe interior to. the exterior of the fuse body, thereby reducing thepossibility that hot gases or flame developed when the fusible link isburned out may find their way to the exterior of the fuse body.

` All of the constructions illustratd and described above arecharacterized by marked simplicity ofdesign and great strength to resistinternal pressure. This great strength is secured by reason of the useof a fuse body which is of considerable thickness Compared to itsexterior diameter and the formation of the fuse body from condensite orother similar moldable insulating material which is nonhygroscopic andtherefore does not vary in physical dimensione with variations in thehumidity of the atmosphere.

By making the passage through the fuse body for the reception of thefuse of small size, the thickness of the wall of the fuse body isincreased for greater strength, there is less space for the storage ofgases developed when-the fusible element burns out and two fusibleelements cannot be used together to increase the carrying capacity ofthe fuse. Also, it will be noted that the rating of the -fuse link maybe read through the opening in the end cap without removing any'part ofthe fuse structure and a new fuse link may be inserted in place of onewhich has been burned out without the employment of any special toolsuch as a screw driver.

I claim: 4

In a fuse a. body of molded insulating ma terial comprisin twosymmetrical parts formed to provi e a passage between the parts andhaving cooperatng tongue and groove means, at opposite sides ofthe-passage to hold the parts in assembled relation, a fusible linkextending through the passage and metal caps threadedly engaging theends of the body and adapted to contact with the ends of the fuse.

In testimony whereof I afl ix my signature. i

WILFORD J. HAWKIN S.

